1. Field of the Invention
The present invention relates to dental articulators which permit a pair of opposing dental casts to be repeatedly positioned adjacent one another and moved away from one another for the preparation of dental prosthesis elements such as crowns, bridges, caps, etc. More particularly, the present invention is directed to a dental modeling system including supports for dental casts, and to an inexpensively formed articulator which permits replication of centric, excursion and protrusive movements while still allowing proper registration of the maxillary and mandibular dental casts.
2. Background of the Invention
Various dental articulators are known in the art to which a pair of dental casts are mounted which simulate the movement of the human jaw. Typically, dental articulators are utilized by dentists or dental technicians to create an accurately fitting dental prosthesis, such as a crown, bridge, or cap. Dental articulators are used to mount castings of a patient""s teeth which are used as a model for the creation of the dental prosthesis. In preparing the dental casts, a dentist normally makes a negative impression of the patient""s teeth, which may be a partial or full arch impression. This negative impression serves as a mold for developing a casting of the patient""s teeth. The negative impression is filled with a pourable casting stone which is allowed to harden and thereby form a replica of the patient""s teeth. The upper and lower castings may then be attached to an articulator which allows the opposing casts to be moved toward or away from one another.
Typically, the dental technician will be working on one tooth or several teeth in one of the dental casts. Therefore, it is necessary for the dental technician to separate the tooth from the rest of the dental cast. This separation is performed by sawing through the casting on opposite sides of the tooth. However, doing so separates the tooth from the remainder of the casting which creates a problem when repositioning the tooth with respect to the remainder of the dental cast.
In order to perform such repositioning, previous methods have been developed whereby one or more pins are inserted into a lower surface of the portion of the dental cast containing the single tooth, and corresponding holes are placed in the base of the remaining portion of the dental cast. However, the requirement for the provision of pins and holes requires additional labor, thereby increasing costs and slowing the process. Further, this method does not necessarily lead to an accurate re-registration of the single tooth with respect to the remaining portion of the dental cast. This technique wherein the model is poured, allowed to harden, then cut into dies, and is then pindexed into another base is known as xe2x80x9ca dry pinning technique.xe2x80x9d
Another method known as xe2x80x9ca wet pinning techniquexe2x80x9d utilizes a tray support member having a plurality of holes therein into which several indexing pins are placed. The tray support member and the indexing pins are then covered with casting material which is either poured directly onto the tray support member, or alternatively, into the negative impression taken by the dentist. The negative impression is then placed over the tray support member and allowed to harden. Once the casting material is hardened, the hardened casting material may be removed from the tray support member with the indexing pins being retained in the casting material. The model may be cut into segmented pieces and returned to the tray support member by placing the segmented portions with their indexing pins back into the indexing holes from which they were taken.
The castings or tray support members may be attached to articulator arms for moving the castings toward and away from one another. However, present commercially available articulators for wet pinning systems are flimsy and do not permit reliable registration of the upper and lower castings with respect to one another. Also, the tray support member onto which the casting stone is poured does not allow positive, accurate, and solid re-registration of a segmented tooth onto the tray support member, thus resulting in improper spatial relationship of the segmented tooth with respect to the remainder of the dental cast, which can result in the formation of an improperly fitting crown, cap, or bridge. Correcting such an improperly fitting dental prosthesis unnecessarily increases the amount of labor, costs, material, and patient""s time in the office or lab.
There is a need in the art for a simple dental articulator which allows better stabilization of the prosthesis element being worked on, without shifting, or movement of the prosthesis dies in the lab while being worked on. There is also a need in the art for a dental articulator which provides accurate registration of the mandibular and maxillary quadrants or arches of a patient""s mouth, while also permitting recreation of the jaw movements of the patient in centric, excursive, and protrusive manners.
The current invention addresses the dichotomy of the xe2x80x9cdry pinningxe2x80x9d vs. wet pinning technique. Historically the dry pinning technique has been accurate but very labor intensive and time consuming. Conversely, the wet pinning technique has been less labor intensive but not as accurate. The current invention addresses both. The truncated pyramids and the tapered and appropriately sized holes, (pins optional) make for an extremely accurate repositioning of the casts. The elimination of separate casts and the need for time consuming pindexing is eliminated.
Another object of the present invention is to provide a dental modeling system which permits the castings to be produced and articulated in the most economical fashion, both in cost and time required to produce an articulated model of a patient""s teeth. Another problem addressed and solved is that of using quickly setting cyanoacrylate glue. The glue slot and glue hole of the invention prevent unnecessary glue from flowing into and onto undesired areas, and therefore reduces the need for cleanup. In particular, skin contact with the glue is prevented.
The above and other objects of the present invention are obtained by a dental modeling system comprising a support for a dental cast, the support including a main body having a top surface and a plurality of registration pins extending upwardly from the top surface, the registration pins being formed integrally with the main body as a one-piece unit, the registration pins each having a pyramidal shape with four sides which taper inwardly extending away from the top surface of the main body. The support may also include one or more apertures located in the top surface of the main body and extending therein. This and another support may include or be attached to an articulator including a first articulator arm having a first hinged portion, a second articulator arm having a second hinged portion pivotally connected to the first hinged portion of the first articulator arm, with one support attached to the first articulator arm for supporting a first dental cast and a second support attached to the second articulator arm for supporting a second dental cast. This support may be used as part of a wet pinning system as described above wherein the casting stone is placed on the support while in the viscous state and allowed to harden on the support.
The articulator of the present invention may be utilized with previously formed and hardened casts (available by different manufacturers) by utilizing an alternative support including a back member and a bottom member which together form an L-shaped main body, with the back member being oriented at approximately 90xc2x0 with respect to the bottom member. The support may be fastened to the previously formed and hardened dental cast by using an appropriate fastener, such as cryanoacrylic glue. Alternatively, the casting may be formed directly onto the L-shaped main body portion, for example, in instances where it will not be necessary to segment the casting into separate elements.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.